Contributions [Abstract]

No definition available.

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- Definition

Defined benefit plan amounts recognized in other comprehensive income loss net actuarial gain loss before tax attributable to acquisition.

+ References

No definition available.

+ Details

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- Definition

For a defined benefit plan, the minimum required employer contribution in the next fiscal year.

+ References

No definition available.

+ Details

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- Definition

For a defined benefit plan, the previous minimum required employer contribution for the period, prior to government enactment.

+ References

No definition available.

+ Details

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- Definition

Refers to the deferral contribution of the month.

+ References

No definition available.

+ Details

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- Definition

Refers to the eligible associates must complete number of years of service

+ References

No definition available.

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- Definition

Other Benefit Plans - Defined Contribution Plan [Abstract]

+ References

No definition available.

+ Details

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- Definition

The amount of prior service cost that would be recognized during next fiscal year.

+ References

No definition available.

+ Details

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- Definition

Number of years service required before retirement benefits vest.

+ References

No definition available.

+ Details

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- Definition

Amount included in accumulated other comprehensive income (AOCI) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position, including gain (loss), prior service cost (credit), and transition asset (obligation).

+ References

No definition available.

+ Details

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- References

No definition available.

+ Details

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- Definition

The amount of contributions made by plan participants. This item represents a periodic increase to the plan obligation and an increase to plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- References

No definition available.

+ Details

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- Definition

The amount of increase related to special termination benefits offered to and accepted by employees in connection with their termination of employment that are only offered for a short period of time. A situation involving termination benefits may also involve a curtailment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Termination Benefits
-URI http://asc.fasb.org/extlink&oid=6526498

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(10)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Target allocation maximum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)(i)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2446-114920

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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- Definition

Target allocation minimum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)(i)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2446-114920

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- Definition

Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position.

+ References

+ Details

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- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

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- Definition

Percentage of employer's matching contributions to a defined contribution plan that vests in a given year.

+ References

No definition available.

+ Details

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- Definition

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

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Defined Benefit and Other Postretirement Benefits - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Trustmark Capital Accumulation Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Years of service required to vest	3 years
Contributions [Abstract]
Expected minimum required contribution, Prior to HAFTA	$ 0
Actual contribution		$ 1,000,000
Expected minimum required contribution in the next fiscal year	0
Expected minimum required contribution, after HAFTA		0
Other Benefit Plans - Defined Contribution Plan [Abstract]
Trustmarks contribution to defined contribution plan	$ 7,000,000	6,700,000	$ 6,800,000
Contributions up to a maximum of eligible compensation	6.00%
Trustmark contributions to the plan	100.00%
Period when associates may become eligible to make elective deferral contributions after employment	30 days
Eligible associates must complete number of years of service	1 year
Estimated future benefit payments [Abstract]
Accumulated other comprehensive loss expected to be recognized during next fiscal year as components of net periodic benefit cost	$ (4,600,000)
Trustmark Capital Accumulation Plan [Member] \| Cash and Cash Equivalents [Member]
Asset target allocations [Abstract]
Target asset allocation, minimum (in hundredths)	0.00%
Target asset allocation, maximum (in hundredths)	10.00%
Trustmark Capital Accumulation Plan [Member] \| Fixed Income Funds [Member]
Asset target allocations [Abstract]
Target asset allocation, minimum (in hundredths)	10.00%
Target asset allocation, maximum (in hundredths)	30.00%
Trustmark Capital Accumulation Plan [Member] \| Domestic Equity [Member]
Asset target allocations [Abstract]
Target asset allocation, minimum (in hundredths)	30.00%
Target asset allocation, maximum (in hundredths)	55.00%
Trustmark Capital Accumulation Plan [Member] \| International Equity [Member]
Asset target allocations [Abstract]
Target asset allocation, minimum (in hundredths)	10.00%
Target asset allocation, maximum (in hundredths)	30.00%
Trustmark Capital Accumulation Plan [Member] \| Other Investments [Member]
Asset target allocations [Abstract]
Target asset allocation, minimum (in hundredths)	0.00%
Target asset allocation, maximum (in hundredths)	20.00%
BancTrust Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pre-tax gain recognized in OCI as a result of the termination of the plan		1,200,000
Other Benefit Plans - Defined Contribution Plan [Abstract]
Contribution to complete the plan termination		$ 334,000
Supplemental Retirement Plan [Member]
Estimated future benefit payments [Abstract]
Accumulated other comprehensive loss expected to be recognized during next fiscal year as components of net periodic benefit cost	$ (864,000)
Accumulated other comprehensive loss expected to be recognized during next fiscal year as prior service cost	$ 250,000